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vfs: Is mounted should be testing mnt_ns for NULL or error.

A bug was introduced with the is_mounted helper function in
commit f7a99c5
Author: Al Viro <>
Date:   Sat Jun 9 00:59:08 2012 -0400

    get rid of ->mnt_longterm

    it's enough to set ->mnt_ns of internal vfsmounts to something
    distinct from all struct mnt_namespace out there; then we can
    just use the check for ->mnt_ns != NULL in the fast path of

    Signed-off-by: Al Viro <>

The intent was to test if the real_mount(vfsmount)->mnt_ns was
NULL_OR_ERR but the code is actually testing real_mount(vfsmount)
and always returning true.

The result is d_absolute_path returning paths it should be hiding.

Signed-off-by: "Eric W. Biederman" <>
Signed-off-by: Al Viro <>
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1 parent 9fe55ee commit 260a459d2e39761fbd39803497205ce1690bc7b1 @ebiederm ebiederm committed with Al Viro Jan 20, 2014
Showing with 1 addition and 1 deletion.
  1. +1 −1 fs/mount.h
@@ -74,7 +74,7 @@ static inline int mnt_has_parent(struct mount *mnt)
static inline int is_mounted(struct vfsmount *mnt)
/* neither detached nor internal? */
- return !IS_ERR_OR_NULL(real_mount(mnt));
+ return !IS_ERR_OR_NULL(real_mount(mnt)->mnt_ns);
extern struct mount *__lookup_mnt(struct vfsmount *, struct dentry *);

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